Quenching fluid coker vapors



June 16, 1959' J. A. POLACK 2,890,999

QUENCHING FLUID COKER vAPoRs Filed Nov. '22. 1955 NAPgTHA LIGHTER FRACTIONATION ZONE GAS OIL QUENCH ZONE 8 RESIDUAL \FROM BURNER TO BURNER Fig. I

Joseph A. Poluck Inventor By CM Attorney United States Patent z,saa,999

QUENCHING FLUID COKER VAPORS Joseph Albert Polack, Baton Rouge, La., assignor to Esso Research and Engineering Company, a corporation of Delaware Application November 22, 1955, Serial No. 548,408

6 Claims. (Cl. 208-127) The present invention is concerned with a method and means for quenching high temperature hydrocarbon vapors that have a propensity to form coke deposits in the quench equipment. More particularly, this invention is directed to a method and apparatus for rapidly cooling or quenching the vaporous conversion products from a fluid coking process with suitable provision being made to prevent coke deposits or formations in the quenching zone.

Briefly, this invention proposes a design of a quench zone cooling high temperature hydrocarbon vapors wherein all equipment surfaces in contact with the hydrocarbon vapors at coke forming temperatures are adequately washed with a liquid or have a continuous liquid film thereon, whereby coke deposits are effectively prevented from forming. To this end, the lowest member of the vapor-liquid contacting means in the quench zone, which is impinged upon by the high temperature vapors, is provided on the underside with a liquid quench oil wash. By suitable design, liquid from the underside of this lowest member and liquid falling on the upper side are directed to the vertical walls of the quench zone, thereby continuously washing the walls.

While the invention is broadly applicable to any process wherein it is desired to quench hydrocarbon vapors initially having a temperature in the range of 825 to 1000 F. or more, such as hydrocarbon vapors from steam cracking processes, catalytic cracking processes, naphtha reforming processes, etc., it is more particularly applicable and will be described in conjunction with a hydrocarbon oil fluid coking process for the production of fuels or chemicals, wherein the formation of coke deposits has presented particular problems. The vapors from this process have a great tendency to rapidly condense, polymerize :and form coke deposits on contiguous equipment surfaces.

The prior art is familiar with residual oil coking processes wherein a charging stock is upgraded by contact with a dense turbulent bed of fluidized solids maintained at a coking temperature in a coking zone. The oil, upon contact with the solids, undergoes vaporization and pyrolysis, evolving relatively lighter, normally liquid hydro carbon vapors and depositing carbonaceous residue or coke on the solids. The necessary heat for the pyrolysis is usually supplied by circulating a stream of the solids through an external heating zone, generally a combustion zone wherein about 15% to 30% or more of the coke make is consumed, and back to the coking vessel. Steam or another relatively inert gasiform medium is used to fluidize the solids in the coking zone and toeffect circulation of the solids. The excess coke produced is withdrawn either continuously or intermittently.

The heat-carrying particulate solids that form the high temperature fluidized coking bed may comprise any suitable, finely divided, substantially catalytically inert refractory solids such as sand, metal particles, spent catalyst, glass beads, and ceramics. Preferably, however, coke particles produced by the process are the solids used. This permits the withdrawing of coke product free from extraneous foreign matter. As this is a fluidized solids process, these coke particles have a size preferably in the range of 40 to 500 microns by screen analysis, although the size in some applications may vary considerably beyond this range, e.g., from 10 to .1000 microns.

The coking temperatures used may vary from 850 to 1600 F. Low temperatures in the range of 850 to 1000 F. are preferred when heavier distillates, e.g., gas oils, are desired as the primary product, somewhat higher temperatures in the range of 1000' to 1200 F. are preferred when lighter distillates, e.g., gasolines, are desired, and higher temperatures are used to obtain chemicals and chemical intermediates.

According to prior practices, the vaporous conversion products, after having entrained solids removed, are passed from the coking zone to a scrubhing-fractionating zone. The vapors are first quenched or rapidly cooled by refluxed oils in the scrubbing zone of the scrub-berfractionator, and heavy ends containing highly refractory materials and catalyst contaminants are preferably separated. The quenched vapors then enter the fractionation zone, the first plate of which consists of a draw-off plate for removing the highest boiling gas oil product and reflux stocks. The heavy ends removed in the scrubhing zone are, preferably, recycled to the coking zone substantially to extinction. To obtain high yields, the initial boiling point of the heavy ends is desirably maintained at the highest temperature possible consistent with securing a gas oil meeting minimum quality standards. Conversely stated, the end boiling point or cut point of the highest boiling gas oil removed as product is maintained as high as possible without exceeding the permissible content of metal or other contaminants in the gas oil. This is done not only to secure higher yields of gas oils but also to decrease the amount of material that must be recycled. A high recycle rate is to be avoided, not only because it is uneconomical per se, but also because a high recycle rate leads to poor product qualities and yields.

In the prior designs, when quenching the vaporous products from the fluid coking zone, difliculty has been experienced in achieving an arrangement whereby eflective quenching is obtained without having objectionable coke formation at some location in the quench zone. Hydrocarbon vapors having a temperature above about 850 F., coming in contact with surfaces at a temperature of about 700 to 1000 F., rapidly condense thereon and the condensate then cracks to coke. Also, some of the scrubbing oil may find its way into the conduit admitting the high temperature vapors to the scrubbing zone and coke therein, eventually blocking the conduit. Poor vaporliquid mixing may result in local points of overheating which also contributes to coke deposits. These coke deposits may become so severe as to render the equipment inoperable and in the least, decrease efliciency. In some cases, the deposits may become dislodged and find a way into the liquid circulation lines.

While other means of cooling the vapors may be used, liquid scrubbing or quenching is preferred so that the vapors can he quickly cooled to' prevent after cracking which results in poor yields and product distributions. Preferably the vapors are cooled below 850" F. in less than 15 seconds. To obtain as high a yield as possible, the true end boiling point of the quenched vapors is desirably maintained as high as possible, around 1000 F. or above. However, the liquid temperature in the scrubbing zone can not exceed about 800 F., because above this temperature, the liquid oil is prone to coke and form liquid phase coke deposits. This means that a true vaporliquid temperature equilibrium cannot be achieved in the quench or scrubbing zone. In some cases, however, it

may be possible to approach the efliciency of one theoretical plate in fractionation in the quench zone. It will be obvious that the highest contacting efficiency possible is desired so as to obtain a gas oil product cleanly separated from the heavier higher boiling contaminant containing ends of the vapors.

It is a purpose of this invention to provide the art with a design that solves the above and other problems, as will appear from the following description during which the attached drawings forming part of this specification are described in detail.

In the drawings:

Figure I illustrates a coking apparatus to which this invention has applicability. A coking vessel with a superimposed quench and fractionation tower is shown.

Figure II illustrates, in enlarged vertical section, an alternative embodiment of this invention.

Figure III illustrates another embodiment of the invention.

In brief compass, this invention proposes apparatus for quenching high temperature hydrocarbon vapors having coke forming propensities which comprises, in combination, a vertically elongated vessel, vapor-liquid contacting means within an intermediate portion of the vessel, the lowest member of the contacting means being a centrally disposed downwardly concave baffle member in horizontal spaced relation to the vertical wall of the vessel; an insulated conduit extending into and terminating in the central bottom portion of the vessel for admitting the vapors thereto, means for withdrawing quenched vapors from the upper port-ion of the vessel, means for admitting a quench liquid to the top portion of the contacting means, means for withdrawing liquid from the bottom portion of the vessel, and means for introducing a quench liquid against the central underside portion of the baflle member in amounts sufficient to provide a continuous liquid film thereover, the horizontal spaced relation being such that liquid from the upper and undersides of the baflle member flows to and continuously wets the,

vertical wall of the vessel.

In its more specific aspects this invention proposes an improved hydrocarbon oil fluid coking process which comprises the steps of converting a heavy oil to vapors and coke by contact with fluidized particulate solids maintained at a coking temperature in the range of 900 to 1600 F. in a coking zone, withdrawing the vapors overhead through an entrained solids recovery zone in the upper portion of the coking zone, thence passing the vapors at a velocity in the range of 30 to 250 ft./ sec. upwardly through a confined passageway into the lower portion of a quench zone superposed on the coking zone, the quench zone including vapor-liquid contacting means in the upper portion, the lowest member of which comprises a cone or dished shaped baffle member centrally disposed in the quench zone in horizontal spaced relation to the vertical Walls thereof, introducing a quench oil into the upper portion of the quench zone, also passing the quench oil against the underside portion of the cone shaped baffie member in a manner to form a continuous liquid film thereover, passing liquid from the upper and undersides of the cone or dished shaped baflie to the vertical wallsof the quench zone therebelow to form a continuous liquid film thereon, maintaining a reservoir of liquid at a temperature below 800 F. in the bottom portion of the quench zone,-below the outlet of the confined passageway, withdrawing liquid from the reservoir and cooling a portion thereof to obtain the quench oil, and withdrawing quenched vapors at a vapor temperature below 850 F., from the upper portion ofsaid quench zone. a r 7 Referring to Figure I, there is shown a fluid coking vessel 1 with an integral superposed combination scrubbingfractionating tower 21. Coker 1 contains a fluidized bed of particulate coke maintained at a coking temperature. The bed has a definite upper level 2 with a dilute or disperse solids phase thereabove. Fluidization gases, e.g., steam or light hydrocarbon gases, are admitted to the base of the vessel by line 3 and serve first to strip coke particles in the lower portion of the vessel and then pass upwardly, fluidizing the solids therein. The fluidizing gas plus the vaporous conversion products pass upwardly through the vessel at a velocity in the range of 0.5 to 5 ft./ sec.

To maintain the coking temperature, solids are preferably continuously circulated via line 4 to an external heating zone and back via line 5. In the heating zone, the solids are heated to a temperature to 400 .F. above the coking temperature. The external heating zone comprises preferably a fluid bed unit wherein the circulated coke particles are partially burnt by contacting a free oxygen-containing gasiform medium, e.g., air. Other means of supplying heat to the coker may, of course, be used. Thus transfer line burners, gravitating bed burners or shot circulation heating systems may also be used.

The charging stock which is to be converted, according to the present invention, comprises, preferably, low value, high boiling petroleum residua having an API gravity etween about -10 and 20, a Conradson carbon content between about 5 and 50 wt. percent and an initial boiling point between 850 to 1200 F. Broadly the present invention may find applicability in the converting of other charging stocks comprising shale oils, synthetic oils, pitches, tars, coal tars, asphalts, cycle stocks, and extracts.

The oil to be converted, which may be suitably pre-' heated, is introduced into the coking vessel at a plurality of horizontal and vertical points via line 10. Upon contact with the high temperature solids, the injected oil undergoes pyrolysis and vaporization depositing carbonaceous residue on the solids and evolving vaporous conversion products. Recycled heavy ends separated from the conversion products can be introduced into the coker either with the fresh feed or lower down in the coker by a separate line.

The conversion products pass through the solids disengaging zone into cyclone system 6, which may comprise several cyclones located in series or parallel, wherein entrained solids are removed and returned to the bed. To inhibit or prevent coking of the cyclone system, additional diluent gas or extraneous hot solids can be in troduced into the cyclone inlet or thereabouts. It is desirable not to remove all entrained solids from the conversion'products as passage of entrained solids through the cyclone to the outlet will prevent or inhibit coke deposits in the lines leading from the cyclones. The higher boiling ends of the vapors comprise largely refractory highly aromatic constituents of unsatisfactory catalytic cracking quality.

One or more nozzles 8 are used to transfer the vapors from the cyclones to the bottom portion of the quench zone through the'liquid reservoir ll contained therein. The nozzles comprise a well insulated conduit terminating in a converging nozzle. The line may be additionally heated as by steam coils if desired. It is preferred to design the converging nozzles such that the vapors emerging therefrom in normal operation have a velocity in the range of 30 to 250 ft. per second, preferably 50 to 100. This velocity is sufficient to prevent liquid droplets or entrained liquid from falling or flowing down into the nozzle. directs the vapors against the lowest disc in the quenching section. Other nozzle designs, however, including ones that direct the vapors diagonally across the tower, may be used if desired.

The vapors emerging from the cyclones are immediately met with a refluxed cooling or quench medium. In this manner, the vapors are rapidly cooled to a temperature below incipient cracking temperatures, i.e., below about 850 F; The quench medium removes from the vapors the heavier high boiling ends. Depending A vertically disposed nozzle 8 is shown which upon the charging stock to the coker, operating conditions, etc.,.these condensed ends have a nominal initial boiling point in the range of 700 to 1000 F.

The condensed ends collect in the bottom portionof the tower in a liquid reservoir 11, and are removed from the tower by line 13. The maximum liquid temperature at the bottom of the tower should not exceed 800 F., preferably 750 F., in order to prevent liquid phase coking in this section. The ends will contain a major proportion of the contaminants and substantially all of the entrained solids in the vapors. A portion of these ends is cooled and recycled via line 14 to serve as a scrubbing or reflux oil. The reflux ratio of the heavy ends can be in the range of 1/1 to 1, based on recycle to coker, and the recycled oil may be cooled to a temperature in the range of 300 to 650 F. This reflux oil descends in the scrubbing zone countercurrently to the vapors, falling over liquid-gas contacting means, e.g., disc and doughnut baffies 7. Preferably, substantially all of the heavy ends are recycled to the coker but a portion or all may be withdrawn as product via line 13.

It has been previously proposed to use fresh feed to the process as the scrubbing oil instead of using recycled ends and such a variation is applicable to the present invention. Specifically, fresh feed can be introduced into the scrubbing zone via line 14, can be collected into the bottom portion of the zone and then can be introduced into the coker with the recycle.

According to this invention, the lowest member of the vapor-liquid contacting means in the quench section consists of a suitably designed conical or downwardly curved baflie or disc 7a that terminates in horizontal spaced relation to the vertical walls of the quench zone. The cone illustrated has a slant preferably of about 10 to 45 from the horizontal. A downwardly curved member can be used in place of a cone. The optimum angle of the cone and its spacing from the wall will vary with specific systems. The angle depends upon the force of gravity, the momentum of the liquid film on the cone,

and the interfacial tension between the liquid and plate or cone.

The scrubbing oil descending from the upper plates maintains the upper surface of disc 7a wet. To wash the underside of the disc or to provide a continuous liquid film thereon, quench oil from line 14 is circulated by line 9 and sprayed on to the underside as by a spray nozzle. More than one nozzle can be used, or a spray ring, or a series of concentric spray rings, can be used in particularly large installations. Means are provided to maintain a liquid film on the nozzles and/or spray rings. The amount of liquid on the upper and undersides of disc 7a is sufiicient and the spacing of the disc is such that the liquid flows from the disc to the walls of the vessel and forms a liquid film thereon. Thus the equipment surfaces in the zone where the high temperature vapors are being quenched to below coke forming temperatures, i.e., below 850 F., defined by the lower disc and the reservoir of liquid, are washed with liquid. By the time the vapors pass the lowest disc, they are sufficiently cooled so as not to have the ability to form coke deposits.

The area between the lower disc and liquid reservoir in normal operation is filled with violently agitated fine mist and the liquid wash provided by this invention effectively prevents this mist from contacting the cooler surfaces and forming coke deposits thereon.

The vapors, after quenching, pass upwardly through the tower and enter a fractionation or continuous rectification zone, the first plate of which comprises a gas oil draw-off plate 15. Gas oil product is withdrawn from this plate by line 16. The portion of the tower above gas oil draw-oil plate 15 may comprise as many fractionation steps and as many side streams may be withdrawn as desired. As illustrated, no further product streams are withdrawn from the tower and the remaining vapors comprising naphtha and lighter compounds arewithdrawn by line 18 and further treated and separated as desired.

Figure II illustrates an alternative means of supplying liquid by gravity to the upper and lower surfaces of the lowest disc in the quench zone, although it is preferred to positively force or spray the liquid on the underside of the bafile. As shown, a scrubbing vessel 50 contains conventional disc and doughnut vapor liquid contacting means 51. Scrubbing liquid introduced into the upper portion of the quench zone cascades over these to the lower portion of the zone as shown by the arrows. In this design two nozzles 53 are used to introduce vapors into the quench zone. The nozzles can direct the vapors vertically upward, or a nozzle 53 with an inclined converging cap can be used to direct the vapors diagonally across the tower to secure better mixing.

The lowest disc 51a in the tower has a collection cup 54 on top that receives liquid from the doughnut baflie immediately above. The collection cup 54 has small openings next to the upper surfaces of bafiie 51 so that some of the liquid flows evenly out over the surface. The remainder of the liquid in collection cup 54 passes through a small downcomer 55 and is directed by a suitably designed distributing cap 56 to flow evenly over the under surface of baflie' 51a. The distributing cap can be made small enough such that coke deposition therein is not deleterious, or can be also washed with liquid, as by overflow from the cap. The liquid on the under surface of the baffle spreads evenly to the outside edge of the disc and proceeds to the wall as shown bythe arrows. This is because the surface tension of the liquid holds it to the surface of the disc until it reaches the lowest point, the outer edge of the disc. The liquid on the underside is preferably given a slightly higher radial velocity by further turning down the edge of the baffle, as shown. The slant of the bafl le is sufiicient to ofi-set any tendency for the liquid to drop off before reaching the edge. This means that although the zone beneath the baffle 41a and above the outlet of the nozzle is filled with a mist, there are no large droplets of liquid falling towards the nozzle outlets.

In other designs, the baffle can be concentrically slotted or perforated, as shown in Figure III, to provide weep holes for passing liquid to the underside of the bathe. A concentric weir 61 is placed on the baffle 60 to provide liquid to the concentric slots 62.

Example In a coking apparatus as shown in Figure I, a residual oil having an initial boiling point of 950 R, an API gravity of 2.5 a Conradson carbon of 30 'Wt. percent and a sulfur content of 3.7 wt. percent is converted at a coking temperature of 950 P. All of the oil is converted to products boiling below 1000 F., with total recycle of 1000 FH-material, amounting to 34 wt. percent and fresh. feed. The vapors at the cyclone have a vapor temperature of 950 F. and a pressure of 11 p.s.i.g.'

The effluent vapors are introduced through two nozzles into the quench zone, which has a diameter of 7 ft., at a velocity of ft./sec., and are immediately cooled to below 800 F. vapor temperature. the vapors are condensed as heavy ends along with any entrained solids that may pass through the cyclone. This condensed material and the scrubbing oil collect in a liquid reservoir in the base of the scrubbing zone, at a liquid temperature of 700 F. The average residence time of the vapors in the coking and quench zones before being cooled to below 800 F. is 15 seconds. A centrally aligned cone shaped bafiie or disc 5 ft. in diameter having a slant of 25 from the horizontal is situated 2 ft. above the outlet of the nozzles. Thereabove are 3 similar discs spaced 3 ft. apart with matching doughnut bafiies having a center opening of 5.5 ft. diameter situated therebetween. 6 bbL/bbl. fresh feed, of heavy ends are withdrawn from 30 wt. percent of the liquid reservoir and are cooled to a temperature of 500 F. to obtain the quench oil. 50% of this quench oil is introduced by a nozzle against the underside of the lowest disc and the remainder is sprayed into the quench zone above the highest disc. The quenched vapors are fractionated to obtain a gas oil having an initial boiling point of 430 F. and a true final boiling point of 1000 F. 55 'wt. percent of the gas oil is cooled to 500 F. and recycled to the upper portion of the quench zone below the first gas oil draw-off plate and the remainder is withdrawn as product. The gas oil product amounts to 55 wt. percent on fresh feed.

Having described this invention, what is sought to be protected by Letters Patent is succinctly set forth in the following claims.

What is claimed is:

1. Apparatus for rapidly cooling high temperature hydrocarbon vapors having coke forming propensities which comprises, in combination, a vertically elongated vessel, vapor-liquid contacting means within an intermediate portion of said vessel, the lowest member of said contacting means being a centrally disposed downwardly concave baflle member in horizontal spaced relation to the vertical wall of said vessel, an inslulated conduit extending into and terminating in the central bottom portion of said vessel for admitting said vapors thereto, means for withdrawing quenched vapors from the upper portion of said vessel, means for admitting a quench liquid to the top portion of said contacting means, means for withdrawing liquid from the bottom portion of said vessel, and means for introducing a quench liquid against the central underside portion of said baflle member in amounts suflFicient to provide a continuous liquid film thereover, said horizontal spaced relation being such that liquid from the upper and undersides of said bafile member flows to and continuously Wets the vertical wall of said vessel therebelow.

2. The apparatus of claim 1 wherein said vessel is integrally superposed on a hydrocarbon oil fluid coking vessel and includes in the upper portion means for fractionally distilling quenched vapors.

3. The apparatus of claim 1 wherein said last named means comprises a liquid distributing cap below and in vertical spaced relation to the central underside portion of said baffle member, said cap being supplied with liquid through a small downcomer from the upper portion of said baflle member.

4. A method of quenching high temperature hydrocarbon vapors having coke forming propensities which comprises introducing said vapors at a velocity in the range of 30 to 250 ft./sec. and a temperature in the range of 825 to 1500 E. into the lower portion of a quench zone, said quench zone containing vapor-liquid contacting means in the upper portion, the lowest member of which comprises a downwardly opening cone shaped baffle centrally disposed and in horizontal spaced relation to the vertical walls of said zone, introducing a quench oil in the upper portion of said quench zone, introducing additional amounts of said quench oil against the underside of said cone-shaped bafiie to form a continuous liquid film thereover, the amount of said quench oil being sufficient to cool said vapors below 850 F. vapor temperature and to V a flow from the upper and undersides of said cone-shaped baffle peripherally to the vertical walls of said quench zone therebelow and form a continuous liquid fihn thereover, withdrawing liquid below 800 F. liquid temperature from the bottom portion of said quench zone, and withdrawing quenched vapors from the upper portion of said quench zone.

5. An improved hydrocarbon oil fluid coking process which comprises the steps of converting a heavy oil to vapors and coke by contact with fluidized particulate solids maintained at a coking temperature in the range of 900 to 1600 F. in a coking zone, withdrawing said vapors overhead through an entrained solids recovery ,zone in the upper portion of said coking zone, thence passing said vapors at a velocity in the range of 30 to 250 ft./sec. upwardly through a confined passageway into the lower portion of a quench zone superposed on said coking zone, said quench zone including vapor-liquid contacting means in the upper portion, the lowest member of which comprises a downwardly concave baffle member centrally disposed in said quench zone in horizontal spaced relation to the vertical walls thereof, introducing a quench oil into the upper portion of said quench zone, also passing said quench oil against the underside portion of said cone-shaped baffle member in a manner to form a continuous liquid film thereover, passing liquid from the upper and underside of said cone-shaped baffle to the vertical walls of said quench zone therebelow to form a continuous liquid film thereon, maintaining a reservoir of liquid at a temperature below 800 F. in the bottom portion of said quench zone below the outlet of said confined passageway, withdrawing liquid from said reservoir and cooling a portion thereof to obtain said quench oil, and withdrawing quenched vapors from the upper portion of said quench zone, the average residence time of said vapors before quenching below 850 F. in said coking and quench zones being less than 15 seconds.

6. In a hydrocarbon oil conversion system wherein a fractionation zone is superimposed upon a hydrocarbon reaction zone, hot hydrocarbon vapors being discharged from said reaction zone into the lower portion of said fractionating zone, and multiple vapor-liquid contacting members are provided in said fractionation zone, the improved method of reducing deposition of carbonaceous matter due to the contacting of said hot hydrocarbon vapors with cool structural surfaces which comprises introducing a hydrocarbon quench liquid against the underside of the lowest vapor-liquid contacting member in said fractionation zone above the point of introduction of said hot vapors so as to form a continuous liquid film thereon, direct contact of hot vapors with the underside of said member being thereby prevented.

References Eited in the file of this patent UNITED STATES PATENTS 1,335,414 Abbey Mar. 30, 1920 1,620,826 Mitchell Mar. 15, 1927 2,734,852 Moser Feb. 14, 1956 FOREIGN PATENTS 1,105,019 France Nov. 25, 1955 

4. A METHOD OF QUENCHING HIGH TEMPERATURE HYDROCARBON VAPORS HAVING COKE FORMING PROPENSITIES WHICH COMPRISES INTRODUCING SAID VAPORS AT A VELOCITY IN THE RANGE OF 30 TO 250 FT./SEC. AND A TEMPERATURE IN THE RANGE 825* TO 1500*F. INTO THE LOWER PORTION OF A QUENCH ZONE, SAID QUENCH ZONE CONTAINING VAPOR-LIQUID CONTACTING MEANS IN THE UPPER PORTION, THE LOWEST MEMBER OF WHICH COMPRISES A DOWNWARDLY OPENING CONE SHAPED BAFFLE CENTRALLY DISPOSED AND IN HORIZONTAL SPACED RELATION TO THE VERTICAL WALLS OF SAID ZONE, INTRODUCING A QUENCH OIL IN THE UPPER PORTION OF SAID QUENCH ZONE, INTRODUCING ADDITIONAL AMOUNTS OF SAID QUENCH OIL AGAINST THE UNDERSIDE OF SAID CONE-SHAPED BAFFLE TO FORM A CONTINUOUS LIQUID FILM THEREOVER, THE AMOUNT OF SAID QUENCH OIL BEING SUFFICIENT TO COOL SAID VAPORS BELOW 850*F. VAPOR TEMPERATURE AND TO FLOW FROM THE UPPER AND UNDERSIDES OF SAID CONE-SHAPED BAFFLE PERIPHERALLY TO THE VERTICAL WALLS OF SAID QUENCH ZONE THEREBELOW AND FORM A CONTINUOUS LIQUID FILM THEREOVER, WITHDRAWING LIQUID BELOW 800*F. LIQUID TEMPERATURE FROM THE BOTTOM PORTION OF SAID QUENCH ZONE, AND WITHDRAWING QUENCHED VAPORS FROM THE UPPER PORTION OF SAID QUENCH ZONE. 